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IC 8971 



Bureau of Mines Information Circular/1984 




Fabrication Manual for a Reduced-Noise 
Auger Miner Cutting Head 

By Mark R. Pettitt and William W. Aljoe 




UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 8971 



Fabrication Manual for a Reduced-Noise 
Auger Miner Cutting Head 

By Mark R. Pettitt and William W. Aljoe 




UNITED STATES DEPARTMENT OF THE INTERIOR 
William P. Clark, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 



Library of Congress Cataloging in Publication Data: 



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Pettitt, Mark R 

Fabrication manual for a reduced-noise auger miner cutting head. 

(Information circular ; 8971) 

Includes bibliographical references. 

Supt. of Docs, no.: I 28.27:8971. 

1. Coal augers— Noise. 2. Coal augers— Design and construction. 
I. Aljoe, William W. II. Title. III. Series: Information circular (United 
States. Bureau of Mines) ; 8971. 



TN295.U4 [TN813] 622s [681'. 76] 83-600382 



CONTENTS 

Page 

Abstract 1 

Introduction 2 

Fabrication instructions 4 

Conclusions 9 

ILLUSTRATIONS 

1. Overall view of standard auger-type continuous miner..... 2 

2. Cutting sequence of auger-type continuous miner 3 

3 . Standard auger miner cutting head 4 

4. Large-core fabrication details 5 

5. Bit spacing pattern on modified auger 5 

6. Fabrication details of helix stiff ener segments 6 

7. Installation of stiff ener segments on auger 6 

8. Fabrication details of reduced-noise auger 7 

9. Addition of sand to cavities 7 

10. Front and rear views of reduced-noise auger 8 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 


dBA 


decibel (A-weighted network) 


in 


inch 


min 


minute 



FABRICATION MANUAL FOR A REDUCED-NOISE AUGER MINER CUTTING HEAD 

By Mark R. Pettitt 1 and William W. Aljoe 2 



ABSTRACT 

After a long series of laboratory and in-mine tests, a cost- 
effective, mineworthy, reduced-noise auger miner cutting head was de- 
signed, fabricated, and field-tested by Wyle Laboratories under con- 
tract to the Bureau of Mines. Compared with standard auger cutting 
heads, the new heads reduced noise by 10 dBA at the jacksetter's posi- 
tion and by 6 dBA at the operator's position. This report contains 
detailed fabrication instructions, including engineering drawings, that 
show how a standard auger cutting head can be modified to produce a 
reduced-noise auger. 



1 Senior research engineer, Wyle Laboratories, Huntsville, AL. 

^Mining engineer, Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA, 



INTRODUCTION 



Auger-type continuous miners are de- 
signed to extract coal from thin seams, 
approximately 26 to 50 in high. Figure 1 
shows one model of auger miner, the Fair- 
child (Wilcox) Mark 21. The two rotating 
augers at the front of the miner cut the 
coal and move it to the chain conveyor at 
the center of the machine. The conveyor 
carries the coal to the rear of the ma- 
chine and dumps it onto a bridge conveyor 
system. The bridge conveyor connects 
with a panel conveyor (panline) , which 
removes the coal from the face area. 

Figure 2 describes the cutting pattern 
of the auger-type continuous miner. Note 
in figure 2 that the anchor jack is 
placed very close to the face before each 
arc-shaped cut is made. On the Mark 21 



miner in figure 1, the hydraulic anchor 
jacks are emplaced remotely by the 
machine operator. However, on the older 
Mark 20 auger miner, the anchor jacks are 
simple mechanical posts, emplaced manu- 
ally by workers called jacksetters. In 
addition, both models of auger miners re- 
quire the presence of timbermen and/or 
cleanup men in the immediate face area. 
Because of their close proximity to the 
cutting heads, the jacksetters, timber- 
men, and cleanup men on auger mining sec- 
tions are exposed to more noise than al- 
most all other workers in underground 
coal mines. 

Typical noise levels during coal cut- 
ting are approximately 108 dBA at the 
jacksetter's position and 102 dBA at the 




FIGURE 1. - Overall view of standard auger-type continuous miner. 



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A Miner pivots on extended right 
pivot jack as it swings to right 
making cut /. Retracted left 
pivot jack swings forward toward 
cut 2 pivot point. 




B Pivoting on extended left pivot 
jack, miner swings to left through 
cut 2. Retracted right pivot jack 
advances toward cut 3 pivot point. 



-..;-■ ■!■.■■■■ ■■ -""v- 




Again pivoting on extended right 
pivot jack, miner swings right, 
making cut J. Retracted left 
pivot jack moves ahead toward 
cut 4 pivot point. 



FIGURE 2. - Cutting sequence of auger-type continuous miner. 



operator's station. 3 Because MSHA noise 
regulations allow only 45 to 90 min of 
exposure per shift at these levels, jack- 
setters and machine operators are often 
out of compliance. 

Although the chain conveyors and drive 
motors of auger-type continuous miners 
are significant noise sources, coal cut- 
ting is by far the dominant noise source. 
To investigate and control coal cutting 
noise, the Bureau of Mines awarded a re- 
search contract to Wyle Laboratories, 
Huntsville, AL. 4 Under this contract, a 
new pair of auger cutting heads were de- 
signed, fabricated, and tested exten- 
sively in an underground coal mine. Com- 
pared with standard (Wilcox) cutting 
heads, these simple, rugged new heads re- 
duced noise by 10 dBA at the jacksetter 's 
position and by 6 dBA at the operator's 

3 Bobick, T. G., and D. A. Giardino. 
The Noise Environment of the Underground 
Coal Mine. MESA IR 1034, 1976, 26 pp. 

4 Pettitt, M. Development of a Reduced- 
Noise Auger Miner Cutting Head (BuMines 
Contract H0188065). Final Report. March 
1983, 200 pp.; available for consultation 
at Pittsburgh Research Center, Bureau of 
Mines, Pittsburgh, PA. 



position. The in-mine tests showed that 
the reduced-noise heads cut as well, 
loaded as fast, and lasted as long as the 
standard heads. 

This manual describes how the standard 
auger cutting head can be modified in 
almost any weld shop to produce the 
reduced-noise head. Design details vary 
for different auger sizes; however, the 
same three design concepts are employed: 

1. The helixes of the standard auger 
cutting head (fig. 3) vibrate violently 
during coal cutting and are the primary 
sources of coal cutting noise. However, 
underground tests have shown that only 
one helix is needed on the auger for ef- 
fective cutting, loading, and cleanup. 
Because the new auger cutting head has 
only one helix, versus two on the stan- 
dard auger, less metal vibrates and less 
noise is generated. Closely spaced bits 
on this single helix smooth out the cut- 
ting forces applied to the head. 

2. The single helix is stiffened by 
increasing the auger's core size and ap- 
plying a conical helix stiffener. The 
higher the helix, the more it vibrates; 



Cutting heftx 



Conveying helix 





FIGURE 3. - Standard auger miner cutting head. 



therefore, the core of a 28- or 32-in- 
diam auger can be enlarged to stiffen 
the helix and reduce its vibration. The 
conical helix stiffener is a second he- 
lix, leaned against and welded solidly to 
the cutting helix. It forms a continuous 
support for the cutting helix and 
greatly increases its stiffness, thus re- 
ducing vibration even further. More than 
one-half of the noise reduction achieved 
with the new auger cutting head results 
from the stiffer helix. 



3. The conical, triangular cavity be- 
tween the helix stiffener and the bit- 
carrying helix is filled with sand and 
sealed. The sand adds mass, which re- 
duces the response of the helix to cut- 
ting impacts and helps dissipate its 
bell-like "ringing" vibration. Almost 
one-half of the noise reduction achieved 
with the new cutting head is due to the 
sand. 



FABRICATION INSTRUCTIONS 



Standard auger miner cutting heads 
(fig. 3) range from 22 to 32 in. in out- 
side (helix) diameter. Ideally, the core 
diameter of the 28- and 32-in augers 
should be enlarged to achieve maximum 
noise reduction. Although figure 4 con- 
tains the details of this modification, 
it is a difficult process that should not 
be attempted by most mine shops. Never- 
theless, significant noise reductions can 



be achieved by adding only the conical 
helix stiffener and sand. This is a rel- 
atively simple process, as described 
below. 

STEP 1. - REMOVE HELIX AND RELOCATE BITES 

Remove the bit-carrying helix, starting 
30° from where the helix attaches to 
the head casting (fig. 3). Weld new bit 



Note 

Cut off second helix 

and discard 




Note: 

Weld on stringers (4 each minimum) 
before burning out core-to keep 
helix in position 



J 

10.25 
burn diam 




MODIFIED HELIX FOR 10- IN CORE 

(Right-hand auger shown-left-hand opposite) 



END VIEW 



Adapter 



6'^-in-ID by 8-in-OD by 
5-in-long mechanical tube 



Note 

All dimensions are 

in inches 





6 ^-in core flange 
cut from standard auger 



4 equally spaced slots by 
3.5 in long (2 places) 

CENTER CORE DETAIL MODIFIED CORE FLANGE 

FIGURE 4. - Large-core fabrication details. 



holders onto the remaining helix at 30° 
intervals as shown in figure 5. 

STEP 2. - PREPARE STIFFENER SEGMENTS 

Using the dimensions in the table in 
figure 6, fabricate the stiffener seg- 
ments from 3/8-in-thick plate. If ade- 
quate metal rolling facilities are avail- 
able, 180 c segments (two per revolution) 
can be prepared. Otherwise, the stiffen- 
er should be cut Into 30° segments (12 
per revolution) . 

STEP 3, - WELD STIFFENER SEGMENTS 
TO AUGER 

Attach the stiffener segments as shown 
in figures 6, 7, and 8. The size of the 
segment and dimension B in figure 6 de- 
termine the angle the stiffener should 



Core 




Stiffener -damper 



Bit holder 



FIGURE 5, - Bit spacing pattern on modified auger. 




Flat pattern for 180° segment, 
3 /e-in plate 



Auger cutting 
diameter, in 


Dimensions, in 


Angle 


A 


B 


C | D /2 


E 


F 


6 


e 1 


e 2 


e 3 


SMALL CORE (6.5-IN DIAM) 


22 


6.5 


5.75 


4.42 


9.0 


7.25 


6.60 


13.85 


124.2° 


20.7° 


37.5° 


24 


6.5 


6.75 


4.29 


10.0 


8.00 


6.12 


14.12 


134.0" 


22.3° 


32.5° 


26 


6.5 


6.75 


4.29 


10.0 


8.00 


6.12 


14.12 


134.0° 


22.3° 


30.55° 


28 


6.5 


7.75 


4.57 


1 1.0 


9.00 


5.93 


14.93 


137.6° 


22.9° 


28.95° 


30 


6.5 


8.75 


4.84 


12.0 


10.00 


5.78 


15.78 


141.84° 


23.6° 


2835° 


32 


6.5 


9.75 


5.09 


13.0 


11.00 


5.64 


16.64 


144.89° 


24.15° 


27.58° 


LARGE CORE (10-IN DIAM) 


26 


10.0 


6.00 


4.50 


II .0 


7.50 


8.05 


15.55 


132.8° 


22.13° 


36.9° 


28 


10.0 


7.00 


4.60 


12.0 


8.38 


7.65 


16.03 


139.7° 


23.28° 


33.3° 


30 


10.0 


8.00 


4.64 


13.0 


9.25 


7.35 


16.60 


145.4° 


24.23° 


30.1° 


32 


10.0 


9.00 


4.90 


14.0 


10.25 


7.21 


17.46 


148.3° 


24.72° 


30.1° 



io"( L / 2 ) 




lead(L) 
FIGURE 6. - Fabrication details of helix stiffener segments. 



180° segment 
( '4 revolution) 



30° segment 
'/j 2 revolution) 




Helix 
( bit holders not shown ) 



Closure 
plate 



Spray nozzle 
FIGURE 7. - Installation of stiffener segments on auger. 



make with the helix. As detailed in fig- 
ure 8, three separate cavities are formed 
by the stiffeners. The largest cavity is 
on the inby (nonconveying) side of the 
helix, beginning at the rear end and ex- 
tending forward; it ends one-fourth revo- 
lution from the start of the head cast- 
ing. The next largest cavity begins at 
the same location, but on the outby (con- 
veying) side of the helix, and continues 
forward to the end of the head casting. 
The smallest cavity is also on the outby 
(conveying) side of the helix and covers 
the remaining section of the head cast- 
ing. Any spray nozzles interfering with 
the installation of stiffener segments 
should be removed, sealed, and relocated. 
All welds for attaching the segments to 
the core, helix, and adjacent segments 
must be continuous to form a completely 



Adapter 

6'^-irHD by 8-in-OD 

by 5-in-long tube 



10-in-OD by 8ln-ID 
mechonical tubing 




LEFT END VIEW 



Note 

All dimensions are in inches 



1.5- 



'/3-in rodius continues tor 180° 
Fill with dry sand before closing 



•5-1 



r- 20 lead - 

53 

65 

PLAN VIEW 



k5- 



— 1.5 




2 typical-, 
3 /e-irHhick pkrte 



0.75 



RIGHT END VIEW 



(Right-hand auger shown, 
left-hand opposite) 



T 



>^-^ 



33.3°typical 

j-fc — < typical 



30- % ^/vjkj % 

typical typical ^VAnnVW 

— 14.3 I— Fill with dry sand 



SECTION BB' 



•>Pical 



SECTION A-A' 

FIGURE 8. • Fabrication details of reduced-noise auger. 



closed cavity for the sand, which will be 
added in the next step. Proper formation 
of these cavities, with the plates at the 
correct angles, is the key to a success- 
ful modification. 

STEP 4. - FILL CAVITIES WITH SAND 

Seal the inby ends of all three cavi- 
ties with closure plates as shown in fig- 
ure 7; then, as shown in figure 9, stand 
the modified auger in a vertical posi- 
tion, with the head casting down. Fill 
the three cavities with dry silicone 
sand, and vibrate the auger periodically 
during filling to compact the sand? a 
welder's chipping tool is sufficient for 
this purpose. When filling is completed, 
install closure plates on the outby ends 
of each cavity (fig. 9). 

STEP 5. - REPAINT THE CUTTING HEAD 

Figure 10 shows the reduced-noise auger 
after the completion of modifications, 



Sand 




Vibrate during filling 
to compact sand 



FIGURE 9. - Addition of sand to cavities. 




FIGURE 10. - Front and rear views of reduced»noise auger. 



including repainting. The top photograph 
shows the inby side of the auger and its 
major components. The bottom photograph 
shows the outby (conveying) side of the 
auger; the locations of the three sand 



cavities described in step 3 can be seen 
here. Figure 10 should be used in con- 
junction with figure 8 to determine the 
proper final configuration of the modi- 
fied auger. 



CONCLUSIONS 



Bureau-sponsored research has shown 
that the noise produced by a standard au- 
ger miner cutting head can be reduced by 
about 6 to 10 dBA through modifications 
to the auger helix. By following the in- 
structions in this manual, any mine shop 



can convert a standard auger into a 
reduced-noise auger. In-mine tests have 
shown that the reduced-noise auger cuts 
as well, loads as fast, and lasts as long 
as the standard cutting head. 



INT.-RU.OF MINE5,PGH.,PA. 27 38 5 



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